Arctic ozone layer depletion reaches record level

Geneva
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The ozone layer's depletion over the Arctic region reached an unprecedented level this spring, due to lingering ozone-depleting substances and extreme cold winter temperatures in the stratosphere, the UN’s weather agency reported this week.

The UN’s World Meteorological Organization (WMO) reports the Arctic’s ozone column suffered a record loss of about 40 percent from beginning of winter to late March, surpassing the previous record of 30 percent over an entire winter.

With the ozone depleted region moving away from the polar region toward the lower latitudes of Greenland and Scandinavia, people in those locations could expect increased ultraviolet (UV) radiation levels in coming weeks. WMO notes that

As the solar elevation at noon increases over the next weeks, regions affected by the ozone depletion will experience higher than normal UV radiation. The public is recommended to stay informed through national UV forecasts.

The stratosphere, just above the troposphere, is the Earth’s second major layer in the atmosphere, and according to Agence France-Presse, contains about 90 percent of the atmosphere’s ozone.

Although ground level temperatures this winter in the Arctic were warmer than average, the stratosphere was colder than a normal Arctic winter.

“The degree of ozone loss experienced in any particular winter depends on the meteorological conditions. The 2011 ozone loss shows that we have to remain vigilant and keep a close eye on the situation in the Arctic in the coming years,” Jarraud added in the WMO statement.

The record loss comes despite the Montreal Protocol, an international agreement designed to phase out chlorofluorocarbons (CFCs) and halons, once found in refrigerators, fire extinguishers and various spray cans. WMO notes that without the agreement, this year’s ozone loss

would most likely have been worse.

Noting 1980 as the benchmark level, the WMO said the ozone layer outside the polar regions is projected to recover to pre-1980 levels in another two to three decades. Because the ozone-depleting substances have long atmospheric lifetimes, it will take several decades for their concentrations to return to that level.

Contrasting that, the Antarctic’s winter/springtime ozone hole, an annually occurring event related to extremely low stratosphere temperatures, is projected to recover between 2045 and 2060.The Arctic ozone hole, according to WMO, will probably rebound one or two decades earlier.

UV-B rays can cause sunburn, skin cancer, cataracts and may cause adverse effects in crops and some marine life.